This application is a continuation-in-part of copending application Ser. No. 07/422,221 filed Oct. 16, 1989 now abandoned.
This invention relates generally to fans, and particularly to those of the class used for engine cooling and like applications. Still more particularly, the invention pertains to a fan of novel knock-down construction designed for the ease of assemblage and high performance characteristics.
By the term "fan" as used herein and in the claims attached hereto is meant any propeller-type device for imparting motion and acceleration to air or other gases and operating on the centrifugal principle. Thus the invention should be construed to comprehend devices that may be commonly classified as blowers.
Internal-combustion engines such as those used on motor vehicles are normally equipped with a fan as a part of the engine-cooling system. Normally mounted on the water-pump shaft driven from the engine via a fan belt, the engine fan functions to provide a powerful draft of air through the radiator. A typical construction of the engine fan has been such that a set of fan blades have been riveted respectively to arms or spokes radiating from a hub. The hub and spokes may be a unitary piece of sheet metal.
This type of engine fan, as so far constructed, has had some shortcomings. Such shortcomings arise from the fact that the fan blades should not overlap, as seen in a front view, to such an extent as to interfere with the riveting of the successive blades to the spokes. Limitations have therefore been imposed on the shape, size and number of fan blades that could be employed. The number of fan blades has had to be reduced if they are each increased in size for higher rates of air delivery. Conversely, if the number of fan blades is increased, the size of each blade has had to be reduced.
Such limitations on the prior art have made it difficult to make the rate of air delivery as high as can be desired, and the air pressure has been easy to pulsate. It might be contemplated to drive the fan at higher speeds for higher rates of air delivery. This solution would not be realistic because, driven at high speeds, the engine fan would generate inconveniently large amounts of vibrations and noise, particularly if it had a relatively small number of blades.